Lets call x the amount of 18% solution and y the amount of 40% solution, and write as equations the info of the problem:
18x + 40y = 10(20)
x + y = 10
lets multiply the second equation by -18 and add to the first:
18x + 40y = 200
-18x -<span> 18y = -180
</span>----------------------
0 + 22y = 20
y = 20/22 = 10/11
and substitute in the original equation:
x <span>+ y = 10
</span>x = 10 - y
x = 10 - 10/11
x = 110/11 - 10/11
x = 100/11
so they have to use 100/11 liters of 18% solution and 10/11 liters of 40% solution
It should be noted that the z score for Thomas test grade is 0.237.
<h3>How to illustrate the information?</h3>
From the information, Thomas took a test in Social Studies and earned a 74.8 and there is the fact that all the students' test grades in the Social Studies class had a mean of 72.6 and a standard deviation of 9.3,
Therefore, the z score for Thomas test grade will be:
= Test score - Mean / Standard deviation
= 74.8 - 72.6 / 9.3
= 0.237.
Therefore, it should be noted that the z score for Thomas test grade is 0.237.
Learn more about standard deviation on:
brainly.com/question/12402189
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Thomas and Pablo began arguing about who did better on their tests, but they couldn't decide who did better given that they took different tests. Thomas took a test in Social Studies and earned a 74.8, and Pablo took a test in Science and earned a 64.1. Use the fact that all the students' test grades in the Social Studies class had a mean of 72.6 and a standard deviation of 9.3, and all the students' test grades in Science had a mean of 61.1 and a standard deviation of 9.8 to answer the following questions.
Calculate the z score for Thomas test grade.
Answer:
First, use the table above to start putting the answers into your memory. Then use the Math Trainer - Multiplication to train your memory, it is specially designed to help you memorize the tables. Use it a few times a day for about 5 minutes each, and you will learn your tables.
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